• Ocean and Polar Research
• /
• 제30권4호
• /
• pp.509-518
• /
• 2008

Distribution of bacterial abundance and production was investigated in seawater around Saemangeum dike 7 times during March, $2007{\sim}July$, 2008. In the inner area of the dike, salinity variation was great due to river runoff from Mangyung and Dongjin Rivers and high chlorophyll a (chl a) concentrations up to $124.3{\mu}g\;l^{-1}$ was found. In the outer area of the dike, salinity was higher than in the inner area of the dike, and chl a was lower up to 10 times than in the inner area of the dike. Thus, the area of Saemangeum showed meso- to hypereutrophic conditions. Bacterial abundance and production ranged from 0.3 to $4.3{\times}10^9\;cells\;l^{-1}$ and from 5.2 to $570 pmol\;l^{-1}h^{-1}$ in outer area of the dike, respectively, while in the inner area of the dike bacterial abundance and production was 3 to 4 times higher ($0.4{\sim}12.7{\times}10^9\;cells\;l^{-1}$ and $12.3{\sim}1309\;pmol\;l^{-1}h^{-1}$, respectively) than those in the outer area. In both areas, bacterial abudance and production was highest in summer and lowest in winter. However, the variations of bacterial parameters was very large in each season. These large variations seemed to be related with the supply of organic matter. Bacterial abundance and production showed significant negative correlations with salinity in the inner area, suggesting that allochthonous organic matter input by river runoff could be an important factor in regulating the distribution of bacterial abundance and production. In addition, bacterial production also correlated positively with chl a in the inner area, suggesting that autochthonous substrate might be another regulating factor of bacterial growth in the area. These results suggest that the supply of both allochthonous organic substrates introduced by river runoff and autochthonous substrates produced by phytoplankon could be important in regulating bacterial growth and utilization of organic matter in the area. Thus, to manage water quality in the inner area of dike, it seems to be important to lower the load of both organic and inorganic nutrients from adjacent rivers.

• Journal of Microbiology and Biotechnology
• /
• 제24권9호
• /
• pp.1196-1206
• /
• 2014

A metagenomic fosmid library was constructed using genomic DNA isolated from the gut microflora of Hermetia illucens, a black soldier fly. A cellulase-positive clone, with the CS10 gene, was identified by extensive Congo-red overlay screenings for cellulase activity from the fosmid library of 92,000 clones. The CS10 gene was composed of a 996 bp DNA sequence encoding the mature protein of 331 amino acids. The deduced amino acids of CS10 showed 72% sequence identity with the glycosyl hydrolase family 5 gene of Dysgonomonas mossii, displaying no significant sequence homology to already known cellulases. The purified CS10 protein presented a single band of cellulase activity with a molecular mass of approximately 40 kDa on the SDS-PAGE gel and zymogram. The purified CS10 protein exhibited optimal activity at $50^{\circ}C$ and pH 7.0, and the thermostability and pH stability of CS10 were preserved at the ranges of $20{\sim}50^{\circ}C$ and pH 4.0~10.0. CS10 exhibited little loss of cellulase activity against various chemical reagents such as 10% polar organic solvents, 1% non-ionic detergents, and 0.5 M denaturing agents. Moreover, the substrate specificity and the product patterns by thin-layer chromatography suggested that CS10 is an endo-${\beta}$-1,4-glucanase. From these biochemical properties of CS10, it is expected that the enzyme has the potential for application in industrial processes.

• Journal of Microbiology and Biotechnology
• /
• 제23권5호
• /
• pp.661-667
• /
• 2013

Lipase-producing bacterial strains were isolated from Antarctic soil samples using the tricaprylin agar plate method. Seven strains with relatively strong lipase activities were selected. All of them turned out to be Bacillus pumilus strains by the 16S rRNA gene sequence analysis. Their corresponding lipase genes were cloned, sequenced, and compared. Finally, three different Bacillus pumilus lipases (BPL1, BPL2, and BPL3) were chosen. Their amino acid sequence identities were in the range of 92-98% with the previous Bacillus pumilus lipases. Their optimum temperatures and pHs were measured to be $40^{\circ}C$ and pH 9. Lipase BPL1 and lipase BPL2 were stable up to $30^{\circ}C$, whereas lipase BPL3 was stable up to $20^{\circ}C$. Lipase BPL2 was stable within a pH range of 6-10, whereas lipase BPL1 and lipase BPL3 were stable within a pH range of 5-11, showing strong alkaline tolerance. All these lipases exhibited high hydrolytic activity toward p-nitrophenyl caprylate ($C_8$). In addition, lipase BPL1 showed high hydrolytic activity toward tributyrin, whereas lipase BPL2 and lipase BPL3 hydrolyzed tricaprylin and castor oil preferentially. These results demonstrated that the three Antarctic Bacillus lipases were alkaliphilic and had a substrate preference toward short- and medium-chain triglycerides. These Antarctic Bacillus lipases might be used in detergent and food industries.

• Asian Pacific Journal of Cancer Prevention
• /
• 제14권12호
• /
• pp.7473-7482
• /
• 2013

The G-protein coupled receptor 87 (GPR87) is a recently discovered orphan GPCR which means that the search of their endogenous ligands has been a novel challenge. GPR87 has been shown to be overexpressed in squamous cell carcinomas (SCCs) or adenocarcinomas in lungs and bladder. The 3D structure of GPR87 was here modeled using two templates (2VT4 and 2ZIY) by a threading method. Functional assignment of GPR87 by SVM revealed that along with transporter activity, various novel functions were predicted. The 3D structure was further validated by comparison with structural features of the templates through Verify-3D, ProSA and ERRAT for determining correct stereochemical parameters. The resulting model was evaluated by Ramachandran plot and good 3D structure compatibility was evidenced by DOPE score. Molecular dynamics simulation and solvation of protein were studied through explicit spherical boundaries with a harmonic restraint membrane water system. A DRY-motif (Asp-Arg-Tyr sequence) was found at the end of transmembrane helix3, where GPCR binds and thus activation of signals is transduced. In a search for better inhibitors of GPR87, in silico modification of some substrate ligands was carried out to form polar interactions with Arg115 and Lys296. Thus, this study provides early insights into the structure of a major drug target for SCCs.

• Bulletin of the Korean Chemical Society
• /
• 제31권9호
• /
• pp.2453-2458
• /
• 2010

Photochemical studies of N-[(trimethylsilyl)alkyl]saccharins were carried out to investigate their photochemical behavior. Depending on the nature of the substrate and the solvent system employed, reactions of these substances can take place by either SET-promoted silyl migration from carbon to either the amide carbonyl or sulfonyl oxygen or by a N-S homolysis route. The results of the current studies show that an azomethine ylide, arising from a SET-promoted silyl migration pathway, is generated in photoreactions of N-[(trimethylsilyl)methyl]saccharin and this intermediate reacts to give various photoproducts depending on the conditions employed. In addition, irradiation of N-[(trimethylsily)ethyl]saccharin produces an excited state that reacts through two pathways, the relative importance is governed by solvent polarity and protic nature. Finally, photoirradiation of N-[(trimethylsilyl)propyl]saccharin in a highly polar solvent system comprised of 35% aqueous MeOH gives rise to formation of a tricyclic pyrrolizidine and saccharin that generated via competitive SET-promoted silyl transfer and $\gamma$-hydrogen abstraction pathways.

• Journal of Plant Biology
• /
• 제35권4호
• /
• pp.393-401
• /
• 1992

한라산의 삼림 토양에서 앞서 보고된 신종 Dictyostelium flavidum Hong et Chang(노랑장대팡이)에 이어서 또하나의 신종이 기록되었다. 이것은 특징적인 넓은 꽃잎 모양의 집합체와 기부부근에 집중적인 긴 가지를 갖는 꽃모양의 군체를 나타내어 Dictyostelium floridum sp. nov. Hong et Chang(한국명 신칭 : 꽃구슬팡이)으로 명명되었다. D. floridum sp. nov.는 위의 특징 외에도, 1) 극낭이 뚜렷한 포자, 2) 기부에서 정단으로 올라갈수록 심하게 가늘어지는 자루, 3) 흔히 원뿔형이거나 구형이 기부, 4) 하나의 점액질에 단단히 묻혀 있는 여러 개의 기부, 5) 여러 층의 세포로 구성된 퇴형의 정단에 의해 특징된다. 또한 이 종은 온도에 매우 민감한 반응을 보이며, macrocyst나 microyst는 형성하지 않는다. 이 종은 처음 토양으로부터 분리된 이후 계속적인 계대배양을 통하여 형태적 특징뿐만 아니라 발생과정 및 성장습성이 자세히 관찰되었으며, 이러한 특징들과 데이터는 다른 유사한 종과 비교되었다. 이 종은 1990년 해발 1600 m 이상의 한라산 침엽수림 토양에서 처음 발견되었으며, 약한 영양배지인 0.1% lactose-peptone 배지에서 Escherichia coli와 함께 $18-22^{\circ}C$에서 이원배양되었다.

• 공업화학
• /
• 제17권6호
• /
• pp.580-585
• /
• 2006

Boehmite 나노졸을 이용하여 자외선 및 열 경화가 동시에 가능한 내구성 코팅재료를 제조하였다. Boehmite (AlOOH) 나노입자에 3-(trimethoxysilyl)propylmethacrylate, (3-glycidyloxypropyl)trimethoxysilane 등의 유기 실란 커플링제를 혼합하는 sol-gel법으로 내구성 코팅 재료를 만들었다. 최초 boehmite 입자가 물에서만 분산 가능하였던 반면, 유기 실란이 도입된 입자는 알코올, tetrahydrofuran, acetonitrile 등의 유기 용매에서도 분산 가능케 되어 코팅 공정상 넓은 응용이 가능하게 되었다. 코팅 박막은 spin 코팅 방식을 이용하여 다양한 기질에 제조되었으며 제조된 박막은 FT-IR, Si/Al CP MAS NMR, UV-Vis spectrophotometer, 연필 경도계 및 FE-SEM, Taber abraser 등의 다양한 방법을 통하여 분석을 실시하였다. 유기실란의 배합 비율을 조절하여 최적화된 경도와 투명성을 갖는 박막을 얻었다. 또한 플라즈마로 전처리된 PMMA기질을 이용한 실험을 통하여 전처리의 효과성을 논의하였다.

• Elastomers and Composites
• /
• 제49권3호
• /
• pp.210-219
• /
• 2014

본 연구에서는 아크릴계 점착제를 합성한 후 이소프렌 액상고무를 블렌드하여 광기능성 시트에 적용될 점착제를 제조하였다. 아크릴 점착제의 모노머로는 butyl acrylate, acrylic acid, 2-ethylhexyl acrylate, 2-hydroxyethyl methacrylate를 사용하였고 용매로는 톨루엔을 사용하였다. 고무계 모노머로는 isoprene 액상고무(LIR-50)를 사용하였고, 아크릴 점착제와의 배합량을 0 ~ 50 wt%로 하여 실험을 진행하였다. 결과에 따르면 LIR-50의 함량이 증가할수록 아크릴계 점착제의 최대 단점이었던 전사현상이 감소하였다. 그 이유는 이소프렌 액상고무의 경우 아크릴 점착제와 달리 극성기가 존재하지 않기 때문에 피착재와 이차결합이 발생하지 않아 경시변화에 따른 전사현상이 감소한 것으로 사료된다. 점착제의 자외선 경화 시 광개시제의 함량이 증가함에 따라, UV에 노출되는 시간이 증가함에 따라 점착제의 경화도가 높아지기 때문에 점착력과 전사현상이 감소하였다. 반면 유지력의 경우는 경화도가 증가하여 분자구조가 망상구조를 이루며 점착제 내부응집력이 증가하기 때문에 유지력은 증가하였다.

• Journal of Microbiology and Biotechnology
• /
• 제30권11호
• /
• pp.1750-1759
• /
• 2020

The characterization of cytochrome P450 CYP125A13 from Streptomyces peucetius was conducted using cholesterol as the sole substrate. The in vitro enzymatic assay utilizing putidaredoxin and putidaredoxin reductase from Pseudomonas putida revealed that CYP125A13 bound cholesterol and hydroxylated it. The calculated K_D value, catalytic conversion rates, and Km value were 56.92 ± 11.28 μM, 1.95 nmol min^-1 nmol^-1, and 11.3 ± 2.8 μM, respectively. Gas chromatography-mass spectrometry (GC-MS) analysis showed that carbon 27 of the cholesterol side-chain was hydroxylated, characterizing CYP125A13 as steroid C27-hydroxylase. The homology modeling and docking results also revealed the binding of cholesterol to the active site, facilitated by the hydrophobic amino acids and position of the C27-methyl group near heme. This orientation was favorable for the hydroxylation of the C27-methyl group, supporting the in vitro analysis. This was the first reported case of the hydroxylation of cholesterol at the C-27 position by Streptomyces P450. This study also established the catalytic function of CYP125A13 and provides a solid basis for further studies related to the catabolic potential of Streptomyces species.

• Ocean and Polar Research
• /
• 제43권4호
• /
• pp.255-267
• /
• 2021

To understand the composition and community changes of benthic species by water depth (5 m, 20 m, 30 m) in the cage facilities, net substrate made of fish cages were installed at intervals of 2 months from March to September 2019, which is the main period of sessile organism recruitment. Water temperature and salinity varied in the ranges of 1~5℃ and 1~4 mg/L at 5 m from June to August, respectively, and less difference was observed according to water depth in other investigation periods. A total of 37 benthic animals were recruited, and Kamptozoa unid., Caprella scaura and Jassa slatteryi were verified during the entire study period. Mytilus galloprovincialis, a Mediterranean mussel, showed seasonality dominant only from spring to early summer (March to July). The community structure classified by temporal and spatial factors, and Bugula neritina, Kamptozoa unid., and Sertularella sp. contributed to the formation of the community. The depth of 5 m was exposed to environmental changes in water temperature and salinity temporally, so there was a seasonal variation in the composition of the sessile organism, but at depths of 20 m and 30 m, there was less significant environmental change and it showed relatively stable than 5 m.